1. Field of the Invention
The present invention relates to a screening apparatus, more particularly, to a screening apparatus removably connected to a prime mover for elevating excavated material and separating the elevated material into fines, or padding, for reintroduction into the excavation and roughs for subsequent introduction into the excavation.
2. Description of Related Art
Underground pipelines are generally installed by placing the pipelines in a prepared trench and then filling the trench to cover the pipeline and restore the surface of the ground to the desired condition. While pipelines are often coated for corrosion control, the pipelines are subject to damage by rocks or other hard, sharp objects typically found within excavated material. The pipelines can also be damaged during installation or during subsequent use of the pipelines. During installation, unintended impact with sufficiently large rocks can damage the pipeline. Even after a successful installation, the pipelines typically exhibit some motion with respect to the surrounding soil, such as by thermal expansion or contraction. Thus, the pipelines must be protected from direct contact with rocks and/or other sharp objects that could damage the pipeline after installation.
Buried cables, including power, electrical or fiber optic cables or lines are also susceptible to damage if not properly padded by fine or soft material. Typically, a layer of sand or soil that is free of large rocks is deposited into the trench immediately adjacent to a pipeline or cable to provide uniform support and to protect the pipeline or cable from damage caused by rocks and/or other objects.
While padding, such as sand or rock-free soil, can be brought in from a location remote from the trench, such acquisition and transport of padding is expensive. For burying lines in remote locations, the transport of the padding can represent a substantial cost and delay to the project.
Therefore, padding machines have been developed, wherein the padding machines move along a pile of excavated material and continuously collects the excavated material, separates the fines suitable for padding, and convey the padding into the excavation to pad the pipeline or cable. Prior padding machines offer an improvement over the hauling of sand from a remote location.
However, as buried lines are becoming necessary in more remote locations, such as windmill and solar collector locations, more varied soil conditions are encountered. As the location of the buried lines is often independent of the type of underlying soil, the excavated soil can have a variety of conditions which can lead to difficulty in loading the padding machine as well as processing by the padding machine.
Therefore, the need exists for an improved screening apparatus that can provide enhanced material handling capability as well as efficient separation of the fines and reintroduction of the fines into the trench while leaving the remaining roughs for subsequent introduction into the excavation.